Not Applicable
Not Applicable
1. Field of the Invention
This invention relates to a medical device delivery systems. More particularly the present invention is directed to stent delivery systems which employ stent retaining socks or sleeves which aid in retaining the stent to the catheter prior to delivery of the stent into a body vessel. The present invention provides for stent end retaining sleeves, wherein each sleeve has two components which are engaged to one another. In at least one embodiment of the invention the sleeve or sleeves are composed of a first tubular portion of material such as polyurethane, the material may be lubricious or have alubricious coating thereupon. The sleeve may also have a second tubular portion composed of a polyurethane-polycarbonate blend such as a mixture of Carbothane(trademark) and Chronoflex(trademark). The second tube has a first end which at least partially overlaps and is engaged to a portion of the first tube. In at least one embodiment of the invention first end of the second tube and at least a portion of the first tube are connected together. A second portion of the second tube is designed to engage a portion of a catheter shaft, while a portion of the first tube is constructed and arranged to be disposed about a stent prior to stent delivery. Other inventive aspects and embodiments of the present end retaining sleeves will be made apparent below.
2. Description of the Related Art
Stents and stent delivery assemblies are utilized in a number of medical procedures and situations and as such their structure and function are well known. A stent is a generally cylindrical prosthesis introduced via a catheter into a lumen of a body vessel in a configuration having a generally reduced diameter and then expanded to the diameter of the vessel. In its expanded configuration, the stent supports and reinforces the vessel walls while maintaining the vessel in an open, unobstructed condition.
Both self-expanding and inflation expandable stents are well known and widely available in a variety of designs and configurations. Self-expanding stents must be maintained under positive external pressure in order to maintain their reduced diameter configuration during delivery of the stent to its deployment site. Inflation expandable stents may be crimped to their reduced diameter about the delivery catheter, maneuvered to the deployment site, and expanded to the vessel diameter by fluid inflation of a balloon positioned on the delivery catheter. The present invention is particularly concerned with delivery and deployment of inflation expandable stents, although it is generally applicable to self-expanding stents when used with balloon catheters.
Inflation expandable stent delivery and deployment assemblies are known which utilize restraining means that overlie the stent during delivery. U.S. Pat. No. 4,950,227 to Savin et al, relates to an expandable stent delivery system in which a sleeve overlaps the distal or proximal margin (or both) of the stent during delivery. That patent discloses a stent delivery system in which a catheter carries, on its distal end portion, a stent which is held in place around the catheter prior to and during percutaneous delivery by means of one and preferably two sleeves. The sleeves are positioned around the catheter with one end portion attached thereto and overlap an end portion(s) of the stent toehold it in place on the catheter in a contracted condition. Each sleeve is elastomeric in nature so as to stretch and release the stent when it expands for implantation. The stent is expandable by means of the expandable balloon on the catheter. During expansion of the stent at the deployment site, the stent margins are freed of the protective sleeve(s). As indicated above, the present invention is particularly directed to stent retaining sleeves having at least two components. In addition to the above, other types of stent delivery sleeves are known.
In some stent delivery devices, a lubricant is applied to the inside surface of the sleeve or the sleeve itself is made to be particularly lubricious. A problem with providing such lubricity is that the lubrication tends to be applied to the entire sleeve, including the portion of the sleeve which is to be affixed to the catheter shaft. The presence of lubrication on the portion of the sleeve which is to be affixed may make it difficult to engage the sleeve to the catheter. In some alternative sleeve arrangements one or more lubricants are added after the sleeve is mounted onto the catheter, but such after-the-fact lubrication is often difficult to apply and may result in uneven lubrication of the sleeve.
The present invention addresses these and other problems associated with many prior sleeve designs by providing each sleeve with two portions, a first portion which is intended to overlie the ends of a stent and which may have an internal surface, which in-whole or in-part, is inherently lubricious or has a lubricant applied thereto, and a second portion which at least partially overlies the first portion and which has an internal surface which may be readily engaged to the catheter shaft as well as the outer surface of the first portion of the sleeve. The overlap between the first portion and second portion also provides the sleeve with a buckle or break point which enhances the capacity of the first portion of the sleeve to retract off of the sleeve as described in detail below. The two portions may be connected to one another by an interference fit, bonding, or welding, such as laser welding.
The entire content of all patents and applications listed within the present patent application are incorporated herein by reference.
This invention provides for a stent retaining sleeve or sleeves which may be employed with a stent delivery system. The inventive sleeves have two components which are engaged to one another. The first component is an elastomeric tube which is designed to be disposed about the end of a stent and the portion of the catheter immediately adjacent thereto. The first component is a tubular portion of sleeve material which includes an inner surface as well as an outer surface both of which may be at least partially lubricated. The second sleeve component is a second tube of sleeve material which is preferably constructed of a different material than the first tube material. In at least one embodiment of the invention the material of the second component has a greater durometer Shore D hardness than that of the first component. A first portion of the.second component overlaps at least a portion of the first component and is engaged thereto. A second portion of the second, component is constructed and arranged to engage a portion of the catheter shaft immediately adjacent thereto. In at least one embodiment of the invention the sleeve may be mounted singly or in pairs about the end or ends, respectively, of a stent on a stent delivery catheter. Where the sleeve or sleeves are utilized in a stent delivery system, the sleeve or sleeves are constructed and arranged to readily retract off of the end or ends of the stent when the stent exerts an outwardly acting radial force on the portion of the sleeve(s) overlying the stent.